cyclic-gmp and Lymphoma

Our previous reports showed that thymic lymphomas arising in TCR transgenic mice are resistant to Ca2+-mediated apoptosis. Here we show that induction of apoptosis in thymic lymphomas involves a process that is cAMP-mediated and which depends on the activation of protein kinase A (PKA) despite the lower level of PKA type I in these lymphomas compared to thymocytes. Further, we show that treatment of the lymphomas with HA1004, a serine/threonine protein kinase inhibitor, restores their susceptibility to ionomycin-induced apoptosis. Results indicate that HA1004-induced restoration of sensitivity to ionomycin proceeds through a PKA-independent mechanism. Moreover, activation of PKA instead of its inhibition induces apoptosis of lymphoma cells.

Topics: Animals; Apoptosis; Calcium; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cyclic GMP; Enzyme Activation; Enzyme Inhibitors; Isoquinolines; Lymphoma; Mice; Protein Serine-Threonine Kinases; Signal Transduction; Sulfonamides; Thymus Neoplasms; Tumor Cells, Cultured

We describe herein functional attributes and generation of immunologic suppressor activity elaborated in response to oncogenic virus infection. Malignant rabbit fibroma virus-induced immunologic suppressor factor (VISF) is a T cell product produced in peak quantities by spleen cells taken from infected rabbits 7 days after infection in vivo. Its production does not appear to require macrophage participation. VISF is highly labile, 3.5 to 12 kDa, and capable of suppressing both B and T lymphocytic responses. Indomethacin and the cyclic nucleotides cAMP and cGMP inhibit its generation. VISF activity is neither antigen nor species specific. It suppresses murine and leporine immune responses to antigens unrelated to the inducing virus. Comparable suppressor activity may be induced by infecting an apparently non-functional rabbit T lymphoma line, RL-5, with malignant rabbit fibroma virus. VISF is principally a suppressor-inducer factor: in vitro, lymphocytes exposed to VISF do not show decreased immunologic responsiveness until 4 days of culture. VISF induces T suppressor cell activity when normal spleen cells are exposed briefly to VISF. Thus, immunosuppressive consequences of malignant fibroma virus infection are partially mediated by a small, non-specific T cell-derived suppressor lymphokine with unique functional characteristics. Non-specific immunologic dysfunction that often attends virus infections may reflect the activity of such factors in humans as well.

Topics: Animals; Cyclic AMP; Cyclic GMP; Depression, Chemical; DNA Tumor Viruses; Female; Fibroma Virus, Rabbit; Gene Expression Regulation; Immune Tolerance; Indomethacin; Lymphocyte Activation; Lymphoma; Mice; Mice, Inbred Strains; Poxviridae; Rabbits; Species Specificity; Suppressor Factors, Immunologic; T-Lymphocytes; Tumor Cells, Cultured; Tumor Virus Infections

Extracts of a mutant S49 lymphoma cell line, termed K30a, hydrolyze cAMP and cGMP at rates much faster than do wild type S49 extracts. This elevated phosphodiesterase activity, called K-PDE, elutes as a single peak of activity on DEAE-cellulose columns (Brothers, V. M., Walker, N., and Bourne, H. R. (1982) J. Biol. Chem. 257, 9349-9355). Direct photoaffinity labeling of K30a extracts with [32P]cGMP results in radiolabeling of a unique polypeptide, not observed in wild type extracts, which migrates in sodium dodecyl sulfate polyacrylamide gels with an Mr = 106,000. The 106-kDa band was identified as the catalytic K-PDE polypeptide based on the following observations: competitive inhibitors and substrates of K-PDE inhibit photolabeling of the 106-kDa band, indicating that [32P] cGMP photolabels the enzyme at its catalytic site; on DEAE-cellulose chromatography the polypeptide that is susceptible to photolabeling co-elutes with K-PDE activity; the 106-kDa band is detectable in extracts of WT X K30a hybrids (where WT denotes wild type) in amounts proportional to the K-PDE activity in the hybrids, but is undetectable in wild type. The hybrid phenotype strongly suggests that the K30a phenotype is not due to mutations that affect either a diffusible regulator of transcription or an enzyme that modifies K-PDE. Although wild type cells contain a minor cGMP phosphodiesterase activity distinct from the major cAMP phosphodiesterase, the wild type cGMP phosphodiesterase is not susceptible to radiolabeling with [32P]cGMP; this rules out the possibility that the K30a phenotype is caused by overexpression of a wild type phosphodiesterase. We conclude that the K30a mutation produced expression of a new species of phosphodiesterase molecule that is not detectably expressed in the parental S49 wild type cell line.

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; 3',5'-Cyclic-GMP Phosphodiesterases; Affinity Labels; Animals; Cell Line; Cyclic AMP; Cyclic GMP; Lymphoma; Mutation; Neoplasms, Experimental; Photochemistry

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; 3',5'-Cyclic-GMP Phosphodiesterases; Animals; Binding, Competitive; Cell Line; Centrifugation, Density Gradient; Chromatography, Gel; Chromatography, Ion Exchange; Cyclic AMP; Cyclic GMP; Kinetics; Lymphoma; Mice; Mutation; Neoplasms, Experimental

Topics: Animals; Antibodies; Antibodies, Monoclonal; Bucladesine; Cyclic AMP; Cyclic GMP; Dibutyryl Cyclic GMP; Immunologic Capping; Lymphoma; Membrane Proteins; Mice; Rabbits; Rats; Theophylline; Thymoma

The present study shows an increased urinary cyclic guanosine 3'.5'-monophosphate (cyclic GMP) excretion rate in children of all age groups bearing malignant tumours or lymphomas. The incidence of increased cyclic GMP excretion was highly significant (79%). Follow-up studies of up to three years have revealed that during periods of remission of malignant disease the urinary cyclic GMP excretion drops to near normal values, whereas recurrences are accompanied by a new increase of cyclic GMP excretion.

Topics: Age Factors; Child; Child, Preschool; Cyclic GMP; Female; Fetus; Follow-Up Studies; Humans; Infant; Infant, Newborn; Leukemia; Lymphoma; Neoplasms; Pregnancy

When crude preparations of protein kinase inhibitor (PKI) are added to homogenates of S49 lymphoma cells, protein kinase activity increases rather than decreases. This is not an increase in the activity of cyclic AMP-dependent protein kinase, which is completely inhibited by PKI, nor an increase in either cyclic GMP-dependent or Ca ++-dependent kinases. The increased kinase activity is not due to PKI itself but to one or more protein contaminants which serve as substrates for an S49 cell kinase which is cyclic nucleotide- and Ca ++ -independent. These contaminating substrates can be readily separated from PKI by DEAE cellulose chromatography. Although the crude PKI preparations sold by the major biochemical supply houses may be satisfactory for some purposes, we suggest that crude PKI be further purified when used to assess kinase activity in systems as complex as homogenates of whole cells. Otherwise, the presence of contaminating proteins in crude preparations of PKI can lead to erroneous conclusions about the type and quantity of protein kinase in the cell.

Topics: Animals; Calcium; Carrier Proteins; Cell Line; Cyclic AMP; Cyclic GMP; Enzyme Activation; Genetic Variation; Intracellular Signaling Peptides and Proteins; Kinetics; Lymphoma; Mice; Molecular Weight; Neoplasms, Experimental; Protein Kinases

Cyclic AMP-elevating agents have been shown to increase the expression of Fc receptors on the Abelson virus-induced pre-B cell tumor ABE-8. Such agents included isoproterenol, PGE1, 3-isobutyl-1-methyl xanthine, and 8 BrcAMP. The positive inductive effect produced by these agents was inhibited by 8 BrcGMP and PGF2 alpha, which putatively elevate cyclic GMP levels. Other agents also shown to induce Fc receptor expression were LPS and certain batches of fetal calf sera. In contrast to the inductive effect produced by cyclic AMP elevating agents, 8 BrcGMP and PGF2 alpha were unable to reverse the increased Fc receptor expression produced by LPS and fetal calf sera. Thus, these latter agents may act via a qualitatively different mechanism in producing a change in phenotypic expression. The results of this study are discussed in terms of the use of tumor cells as a model system for studying the pharmacologic control of lymphocyte differentiation.

Topics: Animals; B-Lymphocytes; Cell Differentiation; Cell Membrane; Cells, Cultured; Cyclic AMP; Cyclic GMP; Dose-Response Relationship, Immunologic; Lipopolysaccharides; Lymphoma; Mice; Mice, Inbred BALB C; Rabbits; Receptors, Fc; Sheep

Topics: Adenosine Triphosphate; Animals; Carcinoma, Hepatocellular; Cell Line; Cell-Free System; Chromatography, Thin Layer; Cyclic AMP; Cyclic GMP; Hot Temperature; Liver Neoplasms; Lymphoma; Pentosephosphates; Phosphorus Radioisotopes; Phosphotransferases; Protein Kinases; Rats; Ribose; Tritium